A display apparatus, in which a screen image is displayed by adjusting the transmission amount of the light emitted from a backlight, as exemplified by a liquid crystal display apparatus, undergoes the occurrence of such a phenomenon called “misadjusted black level” that even a portion, at which the black is intended to be expressed, seems to be bright, and this phenomenon brings about a factor to deteriorate or decrease the image quality (deteriorate or decrease the contrast) in some cases. This phenomenon occurs such that a liquid crystal unit, which adjusts the transmission amount of the light emitted from the backlight, cannot shut off the light sufficiently, and a part of the light is consequently transmitted.
In view of the above, the following technique is used. That is, the backlight is divided into a plurality of light source blocks. The screen image is analyzed for each of areas (divided areas) on a liquid crystal panel corresponding to the light source blocks respectively. The light emission is controlled for each of the light source blocks depending on the luminance (brightness) of the screen image to be displayed on each of the divided areas. This technique is referred to as the local dimming (hereinafter abbreviated as “LD”) control. In accordance with LD, it is possible to display the dark portion more darkly by locally decreasing the luminance of the light source block corresponding to the divided area on which the screen image having the low luminance is displayed, and thus it is possible to suppress the decrease in the contrast.
A technique is disclosed in Japanese Patent Application Laid-open No. 2010-122669 as a conventional technique relevant to the LD control, wherein a still image portion and a moving image portion, which are included in an image, are detected, and the light emission state of a backlight is controlled differently between the still image portion and the moving image portion. In the case of Japanese Patent Application Laid-open No. 2010-122669, the light emission amount is decreased as far as possible in the divided area of the backlight corresponding to the still image portion, and the light emission amount is unchanged as far as possible in the divided area of the backlight corresponding to the moving image portion.